The invention relates to a constant velocity universal ball joint of the fixed joint type, having an outer joint part with curved outer ball tracks extending longitudinally inside, having an inner joint part with curved inner ball tracks extending longitudinally outside, having a plurality of torque transmitting balls which are each guided in outer and inner ball tracks associated with one another, having a ball cage with a plurality of cage windows respectively receiving the balls, wherein the tangential planes at the points of contact of the balls with the outer and inner ball tracks--which points of contact are required for torque transmitting purposes--define a spatial control angle 2K and wherein the superposition of the momentary local relative speeds in the points of contact between the balls and the outer and inner ball tracks defines the rolling error .DELTA.v.
Previously known and produced constant velocity universal ball joints have a load bearing capacity which is greatly reduced at large articulation angles. In some instances, such joints generate a scratching noise at large articulation angles. Said noise is attributed to sliding movements between the balls and the ball tracks, which sliding movements are caused by the rolling error existing in each constant velocity ball joint. It has to be taken into account that the loads on individual balls and the rolling error of the balls vary considerably during one rotation of the joint and that the highest ball loads acting as normal forces occur approximately in the points of minimum control angles where at the same time large rolling errors occur. In consequence, there occur high sliding percentages in the contact points under high normal forces and thus a high friction energy loss. A high degree of wear, high temperatures and a tendency for scratching noises to occur constitute further disadvantages.
The rolling error .DELTA.v can be regarded as being the momentary speed component of the movement of a ball centre, with which speed component the ball would leave the cage plane if it were not held back by the cage and if no sliding would occur in the ball contact points with the ball tracks of the outer joint part and the inner joint part (ball hub).
When the CV joints are in an articulated condition, the balls, as a result of the rolling error .DELTA.v, usually have the tendency to leave the cage plane. This tendency has to be counteracted by the cage in that it displaces the balls against their rolling tendency relative to the ball tracks.
Without the function of the cage, the balls would remain in the angle-bisecting plane only if the rolling error .DELTA.v equals 0. Under the latter condition, the ball would roll in its two contact points, and though would remain on its position in the cage plane.
The rolling error .DELTA.v depends on the respective phase angle .theta. of a ball with reference to the joint articulation plane extending through the axes of the joint components.
The rolling condition of .DELTA.v equalling 0 under which the balls remain in the cage plane of their own accord, during one joint rotation, is met by each ball only in two phase positions.
At all the other phase angles the cage has to hold the balls in the cage plane, with the balls sliding in the points of contact with the ball tracks.
The course taken by the supporting forces acting on the balls also changes as a function of the phase angle .theta.. Said supporting forces are the normal forces acting on the balls at the contact angle .delta..
The disadvantage of the prior art joints is that in the regions with high supporting forces there exists a considerable rolling error. High rolling errors, i.e. high sliding percentages combined with high supporting forces result in high friction and thus a high degree of wear, but also in high inner joint forces which reduce the maximum load bearing capacity of the joint, especially of the cage.